题目内容：

英语作文时态问题：when
let me give you an example.If there are something happened in our class,she could knew a lot of details than we were.请帮我找出这句话的错误和原因
我和我的朋友已经毕业，我要写一篇比较她和另外一个人的英语作文，在说道：when we go outside，she loves to buy a lot of things to showing off 的时候，这句话的语法是不是有错误？时态的错误？我分不清时态的转换和用法。